The most basic form of amplitude modulation is known as double-sideband AM, so called because mirror-image sidebands are produced above and below the carrier frequency. Early researchers found that they could use simple band-pass filters to eliminate one of the sidebands and even the carrier signal, improving the ratio of information-bearing power to total transmitted […]
FAQ
Microwaves and the Havana Syndrome
Leland Teschler • Executive editor The National Academy of Sciences recently released its conclusions about what sickened dozens of American Embassy diplomats in Cuba, a phenomenon dubbed the Havana Syndrome. Though the panel reached no definitive conclusion, it found pulsed RF (a.k.a. directed microwave energy) was the most likely cause. Panel members could not rule […]
Looking for ghostly goings-on with a milligauss meter
Tune in to TV shows that are purportedly about ghost hunting and you’ll often see people wandering around in the dark with an instrument called a milligauss meter. A milligauss meter detects changing magnetic fields. (It won’t detect static fields as from a bar magnet.) When a milligauss meter shows a reading during a ghosting […]
Tools: Galileo and the sector
Galileo was born the same year as William Shakespeare. He was a builder or instruments and used them to measure earthly and extraterrestrial phenomena. He published his findings, only to become embroiled in disputes with the religious authorities. In a trial before the Inquisition, he was compelled to recant his views and he spent his […]
Integration and differentiation operations and how they appear on a scope
Differential calculus is the study of rates at which quantities change. To find the derivative of a waveform at a specific point, we draw a tangent line through the point. The slope of the line, Δy/Δx, equals the derivative of the function at that point. Integral calculus quantifies the area bounded by a curve and […]
Online calculators that are handy for EEs
Online calculators have proliferated. Consider that one site dubbed omnicalculator.com now hosts over 1,800 online calculators in various disciplines. But when it comes to electronics and engineering, the pickings are slimmer. Calculatoredge.com provides numerous online calculators for engineers of which a little over 100 are in electronics and electrical engineering. That brings us to Digi-Key […]
Audio measurements and Dolby, dbx noise reduction
Audio engineers in the 1970s became aware that many of the traditional distortion mitigating methods were unsatisfactory. In this context, dbx and Dolby noise reduction systems emerged. Dbx Type I and Type II vastly improved audio fidelity in analog tape reproduction. Dbx-TV is another system component that provides stereo sound for TV systems in the […]
Attenuation networks and their measurement
An attenuator is a four-terminal, two-port network that reduces the amplitude of a signal without distorting its waveform. Attenuators are used in electronic instrumentation to precondition a signal for measurement and display. For example, the commonly-used 10:1 oscilloscope probe attenuates the signal voltage upstream from the analog channel input by a factor of ten, letting […]
The difference between LEDs and photovoltaic cells
LED’s and photovoltaic cells play increasingly prominent roles in our world. Both are semiconductor diodes. The LED or light-emitting diode emits light while the photovoltaic cell converts light to electricity. The LED is a diode that emits light only when forward-biased. Under a forward voltage bias, electrons cross from the n-region and recombine with the […]
Review: Using the Fluke 438-II motor analyzer
Fluke has come out with another superb electrical measuring instrument. It is the Fluke 438-II Motor Analyzer. Owners of the previous Fluke 435-II Power Quality Analyzer can download an upgrade that will add Motor Analyzer functions to their existing equipment. Full documentation including specifications and owner’s manuals for both of these members of the oscilloscope […]